Apparatus for heat-treating tandem bearings



March 24, 1942.

H. E. soMEs 2,277,372 APPARATUS FOR HEAT-TREATING TAKLSEM'BEARINGS Filed July 1, 1938 I I i INVENTOR.

Howard 151 50211425 ATTORNEY.

Patented Mar. 24; 1942 APPARATUS non HEAT-TREATING TANDEM names Howard E. Somes, om Pointe Park, Micln, assig'nor to Budd Induction Heating, Inc., Philadelphia, Pa., a corporation of Michigan Application July 1, 1938, Serial n 216,931

Claims.

The present invention relates in general to electrical heating and more-particularly to differential heat treatment by electro-magnetic induction for effecting localized hardening of an object hardenable by heat treatment.

The main object of the invention is the provision of means for simultaneously hardening different portions of an object such for example as the bearing surface portions of tandem bearings. 4 s

A special object of the invention is the provisionof means for simultaneously heat treating the bearing'surface portions of conical tandem bearings such for example as are used in the hubs offront wheels of automobiles. f

mobile wheel having a pair of conical tandem bearings l5 and I6.

The induction tool comprises a central hollow tubular frame element ll in which are mounted The hardening of conical tandem bearings,

particularly the conical tandem bearings in an automobile hub, presents specialv difficulties in axially the same as the bearings to be heat treated to enable them to bepositioned in both bearings at the same time. Toenable both-coils of the single heating tool to be inserted into the hub from one end, it is, of course, necessary that any outward flareoi' the leading coil'to a diam- 'eter greater than the smaller diameter of the far tapered bearing is to be avoided. The leading coil is, therefore, of cylindrical form with a diameter slightly less than the smallest diameter of the far bearing to allow for substantial clearance' between the coil and the bearing, and specialmeans are provided to oiiset the eiIects of the increased air gap between the far end of the leading coil and the enlarged end of the conical bearing, which means consists in general of means for conducting the flux around the tar end of the leading coil into the'outer end of the far bearing in a direction parallel to the elements of the cone-shaped bearing surface.

The above and otherobjects and advantages of the invention will be'more clearly understood from a perusal of the following specification and the drawing accompanying the same.

The drawing is a vertical axial section showing the heating tool in position in a work-piece and the elements accessory thereto.

Referring to the drawing in detail, Ill represents a metal supporting bed on which is secured by means of suitable screwbolts II a work-supporting ring I2 provided with an annular rabbeted recess l3 arranged to receive theworkpiece. it here shown as the front hub of an auto-- a pair of axially spaced and axially aligned inducing coils l8 and I9, each coil provided with a core element 20 and 2| respectively, built up of radially arranged laminations taperedto form a solid mass of laminated material. The laminated core' 2| of the lower or leading coil I9 is assembled and held in place on the lower end of the tubular frame element ll, about the lower extension 22 'of reduced diameter, by the clamping ring 23 held in clamping engagement with the laminated core by means of the washer 24 and clamping nut 25 threaded on to the lower reduced end 28 of the tool shaft 21 on which the heating tool is carried for movement into and out of operative relation with the work-piece ll by suitable operating means not shown but which maybe like that shown and described in my copending application Serial No. 96,346, flled August l'l, 1936. The laminations of the coil element 2| of the leading coil are held against radial -displacement by means of engagement of the'annular locking ridges 28 and 29 with complementary notches in the laminations. The

laminations of the upper or trailing coil are clamped in position between the upper clamping shoulder 30 formed at the upper end of the frame element l1, and the lower clamping ring 3|, the latter being held in position by a resilient split ring 32 sprung into an annular recess in the frame element. The laminations of this core are securedagainst radial displacement by annular 4 locking ridges on the shoulder 30 and ring 3|, in

a manner similar in all respects to that in which the lower laminations 2| are secured. The inducing coils l5 and I6 are formed of a continuous conductor element 33 which is led in through preferably a continuous .portion of the conductor, through the space between the upper and lower core elements and their adjacent radial flanges to the recess in the lower core element 2i. The conductor then extends around the lower core element to form the lower inducing helix or coil which at its lower terminal is electrically connected through the radial extension conductor element 31 to thebody of the frame element ll which latter thus forms the return circuit conductor for the two coils'connected in series. The convolutions of the coils are insulated from each other and from their cores by suitable insulation 35, insulating sleeves or bushings 36 being provided for the conductor where it passes through the radial flanges of the cores. The

conductor forming the coils l5 and i6 is here shown solid but it is to be understood that it may be a hollow or tubular conductor permitting the use of a cooling fluid in well known manner such as that shown in my copending application above referred to. In small work of the type here shown where brief applications of energy are used, for example a rate of input in the neighborhood of 300 kw. for an interval say of less than 3 seconds, liquid cooling of the conductor is not absolutely necessary, especially where the intervals between applications of energy are large in comparison with the brief time of application. the larger time being consumed in the quenching, unloading, and reloading all of which occur between applications of energy.

Inasmuch as the heating tool is intended to be brought into operation with the tandem bearings in the work-piece from above, the upper or trailing coil l5 may be of conical form to conform with the cone-shape of the upper bearing, but the lower or leading coil I9 must, throughout its radial extent, be less in diameter than the smallest diameter of the lower bearing with sufilcient clearance to insure against contact thereparallel to the geometrical elements of the conical bearing face. This means is comprised of the ring-form element 38 built up of radially arto the bearing portion will be guided around the end of the coil and into the end of the bearing portion in a direction parallel to the elements of the cone-shaped bearing portion.

The laminations 38 are held in place and against radial displacement by dove-tail projec tions held in the annular dove-tail rabbet 33 formed in the ring element l2 near the lower end of the opening therein.

Electrical connection with the upper end of the coil conductor 33, is established with the outer conducting sleeve 40 surrounding the tool shaft 21 by means of the connecting lug 4| secured to the sleeve 40, the sleeve 40 being electrically insulated from the tool shaft 21 as indicated in the drawing. The tool shaft and sleeve thus form insulated concentric terminals through which current may be supplied in any suitable or other known manner such as that indicated in my copending application above referred to. In the present instance, connection with the source of alternating current supply of the desired frequency is indicated diagrammatically, such source 42 being connected with the concentric terminal elements 43 and 21 through suitable leads 43 and 44 and suitable switching means 43. Inasmuch as both coils are connected in series, power factor correction for both may be attained through the use of a single capacitance 46 connected across the outside terminals. Inasmuch as the coils are connectedin series a voltage considerably higher than that necessary for a single coil would be required but with the advantage that power factor adjustment may be accomplished with a condenser of considerably lower capacity than would be required were the coils connected in parallel.

In addition to compensation for the increased air gap at the end of the lower bearing by the use of the low reluctance bridging element 33, the leading coil I9 is provided with a greater number of turns in proportion to the upper coil thus giving a slightly stronger field to compensate for the extra long path given the magnetic flux in its passage around and radially away from the end of the coil into-the end of the lowei bearing portion.

In operation, with the hub element I4 placed in the holding ring l2 as shown in the drawing, and the annular bridging element 38 extending upinto the rabbeted end of the hub, the heating tool is moved downinto the hub from the top end to bring the inducing coils l8 and I! into operative relation with the bearing portions l5 and I6 respectively whereupon alternating current of the desired voltage and frequency is supplied to both coils in series from the source 42 over a path which may be traced from the source 42, over conductor 43, connecting lug 4|, upper extremity of conductor 33, coil 18, connection 34, coil is, extension 31, frame element 22, tool shaft 21, and back over lead 44 to the source-42. Energization of the coils I8 and 19 produces annular induced currents in the respectively adjacent bearing portions of the hub, the annular currents being confined in the main to a zone near and including the bearing surface and substantially parallel thereto as indicated by the relatively heavier sectioned zones near the bearing surfaces. This holding of the induced current path in the zone near the bearing surface is made possible in the case of the upper coil by the radially outwardly extended portions of the laminated core 20 which guide the flux around the ends of the coil into the bearing portion I5 along lines substantially parallel to the elements of the coneshaped bearing surface-and in the case of the lower coilby the upper radial extension of the core 2| and the laminated ring element 38 which act to guide the flux around the ends of the coil into the ends of the bearing portion along lines parallel to the elements of the cone-shaped bearing portion. It will be noted that the flux-guid ing element 38 in addition to its function of guiding the flux into the bearing portion in the proper direction, also acts as a shield to protect the relatively thin lower rim of the hub from the current inducing flux.

While I have herein shown and described a specific embodiment of my invention for the sake of disclosure, it is to be understood that the in-.

vention is not limited to such a specific embodiment but contemplates all such modifications-and variants thereof as fall fairly within the scope of the appended claims.

What I claim is: i

l. Apparatus for heat treating tandem reversed conical bearings comprising a pair of inducing coils arranged coaxially in tandem on a central frame element for movement one in lead of the other through one end of the tandem arrangement of bearings each into one of the two bearings, the leading coil throughout its length other, comprising a tapered substantially to the bearing.

2. Apparatus for heat treating a pair of tandem conical bearings flared away from each conical-form inducing coil and a cylindrical inducing coil mounted coaxially on a common frame element and spaced axially from each other with the small diameter end of the conical coil adjacent the cylindrical coil, and a flux conducting element for said cylindrical coil separable therefrom and arranged to extend from the end of the cylindrical coil far hest from the conical coil first radially outwardly and then toward the other end of the cylindrical coil.

3. Apparatus for heat treating a pair of tandem conical bearings flared away from .each other, comprising a conical-form inducing coil tapered substantially to the angle of one of the bearings and proportioned to lie therewithin with appreciable clearance, and a cylindrical inducing coil proportioned to lie within the other bearing with appreciable clearance at the small end of the bearing, said coils being mounted coaxially from the end of the coil into the large diameter end of the surrounding bearing in a direction substantially parallel to the elements of the conical face of the bearing.

, 6. Apparatus forheat treating a pair of tandem conical bearings flared away from each other, comprising a conical-form inducing coil tapered substantially to the angle of one of the bearings and proportioned to lie therewithin with appreciable clearance, and a second inducing coil of circular section proportioned to pass through the small end of either bearing, said coils being mounted coaxially on a common frame element and spaced axially from each other to simultaneously lie each within one of the bearings, and flux conducting elements for said coils extending radially outwardly from the ends thereof a dis tance greater than said clearance so as to radially overlap the geometrical elements of the cone surfaces of the bearings.

, 7. A compound work head for simultaneously heat treating by electro-magnetic induction of surfaces of different contour comprising a work coil of a contour similar to the contour of the one surface and a work coil dissimilar to the contour of the other surface mounted upon a common support for common movement into juxtaposition to the surfaces of different contour to be treated, together with means associated with on a common frame element and spaced axially from each other-to simultaneously *lie each' within one of the bearings, and a flux conducting element for the cylindrical coil separable therefrom and arranged to conduct flux from the end of the coil into the large diameter end of the surrounding bearing in a direction substantially parallel to the elements of the conical face of the bearing.

4. Apparatus for. heat treating. a pair of tandem conical bearings flared away from each other, comprising a conical-form inducing coil angle of one of the bearings and proportioned to lie therewithin with appreciable clearance, and a cylindrical inducing coil proportioned to lie within the other bearing with appreciable clearance at the small end-of the bearing, said coils being mounted coaxially on a common frame element andspaced axially from each other to simultaneously lie each within one of the bearings, and flux conducting elements for said coils extending radially outwardly from the ends thereof a distance greater than said clearance so as to radially overlap the ,geometrical elements of the-cone surfaces of the bearings.

5. Apparatus for heat treating a pair of tandem conical bearings flared away from each other, comprising a conical-form inducing coil tapered substantially to the angle of one of the bearings and proportioned to lie therewithin with appreciable clearance, and a'second inducing coil of circular section proportioned to pass through the small end of either bearing, said coils being,

mounted coaxially'on a common frame element and spaced axially from each other to sixnultaneously lie each within one of the bearings, and a flux conducting element'for the second coil separable therefrom and arranged to conduct flux the work coil of dissimilar contour to compensate I for the irregularity of flux produced by such dissimilarity of contour, and thereby attain relative treatment of the associated uniformity of heat surfaces.

8. work head adapted for" heat treating spaced surfaces on a workpiece by electromagnetic inductionand comprising a support, a plurality of inducing coils, the leading one of which is cylindrical and the trailing one conical, said coils having approximately the same spaced relation on said support as said surfaces to be treated have upon the workpiece, a core for each coil independent of the other and providing a flux path independent of the other core and coil,

and means connecting said high frequency current. I

9. An apparatus'for heat treating a work piece having coaxial oppositely inclined conical surfaces by electromagnetic induction, which includes inducing cores longitudinally spaced about the same amount as said surfaces, one of said coils being also conical and the second being substantially cylindrical and branching at an angle coils to a source of with respect to its conical surface, said second coil being constructed to create a greater flux density than the first coil to compensate for reater separaion of th second coil and its work than the first coil and its work.

10. An apparatus for heat treatment by electromagnetic inducticn, a work piece having surfaces of revolution tangents to which in the same plane form an angle, said apparatus including longitusaid coils having dinally spaced inducing coils separated substantially the same amount as said surfaces, one of said coils having its plane substantially parallel to one of the surfaces of the work, the other of the plane of its convolutions forming an angle to the other work surface, the second coil having greater flux inducing turns than does the first.

-' HOWARD E. SOMES. 

